How a public domain sender address affects email deliverability
In short: A public domain sender address, such as one from Gmail, Yahoo, AOL, or Outlook, hurts deliverability because you can't authenticate a domain you don't own, mailbox providers distrust it, and recipients don't recognize your business. Zoho Campaigns doesn't let you send campaigns from one. Use an email address on your own domain and authenticate that domain instead.Whenever you send campaigns, they will be delivered to the receiving server of the respective mailbox provider. The receiving server will offer inbox placement after carefully scrutinizing the email. If the emails are from a source that the mailbox provider doesn't recognize or considers suspicious, the receiving server may reject them.
Mailbox providers consider a lot of factors before making inbox decisions. The sender address is one of those factors that plays a huge role in determining inbox placement for your campaigns. There are two types of domains from which emails are being sent.
Public domain: A public domain email address is one provided by free email services such as Gmail, Yahoo!, AOL, Outlook, etc.
Business domain: A business domain email address is one used by business to send marketing emails, newsletter and transactional emails. Example: A company called Zylker Financial might use addresses like firstname@zylker.com.
At Zoho Campaigns, we strongly urge our users not to use a public domain sender address to send marketing emails as it will lead to deliverability issues. Let's dive deep and learn more about the drawbacks of using a public domain sender address and how it affects email deliverability.
Implementation of DMARC by mailbox service providers
DMARC (Domain-based Message Authentication, Reporting, and Conformance) is a security mechanism that you can implement to prevent spammers from using your sender domain to perform phishing and spoofing activities. Most mailbox providers have started implementing DMARC to safeguard their sender domain.
DMARC can be implemented only for a business domain sender address and not a public domain sender address, because you can't publish DNS records or sign email for a domain you don't own. Implementing DMARC eliminates the probability of fraudsters using the sender domain of a business to perform phishing and spoofing activities. When making inbox decisions, mailbox providers give additional weight to emails from a business that has implemented DMARC. For senders of 5,000 or more emails a day it is also a requirement: Gmail and Yahoo (since February 2024) and Outlook.com (since May 5, 2025) require SPF, DKIM, and DMARC. DMARC checks whether the domain in your From address aligns with an authenticated domain, which a public domain address can never do for you. See domain authentication.
How Gmail reacts to emails sent using a public domain
Gmail may push emails from public domain addresses to the spam folder, and it may warn recipients that the message seems dangerous or that it was unable to verify the sender domain:
Recognition and trust
Whenever people receive an email, the first thing they notice is the sender address. When they recognize the sender, they're more likely to open the email. When people receive marketing emails from a public domain sender address, they may become hesitant to open it. There are chances for them to mark the email as spam.
For example, if recipients receive an email from patricia.b@gmail.com, they are likely to wonder about the email's origin. On the other hand, if the sender address is patricia.b@zylker.com, the recipients can immediately recognize that the email comes from the company Zylker, and this familiarity will help them trust the domain. So we always urge our users to use a business domain sender address to send their campaigns.
If you use a public domain sender address to send marketing emails, your contacts are more likely to leave your email unopened. Nowadays, mailbox service providers consider email engagement to make inbox decisions. If mailbox service providers identify that your emails are left unopened, they may assume that their users are not interested in receiving your emails and may deny inbox placement for your future emails. The only way to achieve the desired conversions is by using a business domain sender address and authenticating it.
How Zoho Campaigns handles a public sender domain address
Zoho Campaigns doesn't allow you to send email campaigns from a public domain sender address, such as an address from Gmail, Outlook, Yahoo, or AOL. If you try to add a public domain address as a sender address, Zoho Campaigns shows an error and doesn't add it. To send a campaign, add a sender address on your own domain, verify it, and authenticate the domain.
What happens when you use a public domain address in Zoho Campaigns?
Situation | What happens in Zoho Campaigns | What to do |
You add a public domain address as a sender address (Settings > Email > Senders and Authentication > Add Sender) | An error appears and Zoho Campaigns does not add the address. | Enter an email address on your own domain instead. |
You sign up for Zoho Campaigns with a public domain email address | The address is added to your sender addresses under Settings > Email > Senders and Authentication. | You can't send campaigns from it. Add a sender address on your own domain. |
You create an email campaign and try to send it from that address | An alert tells you to add an email address from your own domain as the sender. | Follow the steps below, then send the campaign again. |
If you signed up with a public domain address, you will usually discover this restriction only when you try to send your first campaign, because the address you signed up with is already in your sender list.
How do you start sending campaigns after the alert?
To send campaigns from Zoho Campaigns after you see the alert, add a sender address on your own domain, verify it from the verification email, authenticate the domain (recommended), and then send your campaign. Follow these steps:
- Click the Settings (gear) icon in the top-right corner, then select Email > Senders and Authentication.
- Click Add Sender in the top-right corner.
- In the Add Sender Address panel, enter the Name your recipients will see and an email address on your own domain, such as patricia.b@zylker.com.
- Open the verification email that Zoho Campaigns sends to that address and follow its instructions to verify the address. Until you verify it, the sender address shows a Pending status.
- Authenticate your domain. We recommend this step. On the Senders and Authentication page, click Setup next to your domain to open the Authenticate Your Domain window, and add the SPF and DKIM records it shows to your domain's DNS settings.
- Create your email campaign again, choose the verified sender address as the sender, and send the campaign.
Why does Zoho Campaigns block public domain addresses?
Zoho Campaigns blocks public domain sender addresses because you can't authenticate a domain that you don't own, so the email would fail DMARC alignment and would likely be rejected, sent to spam, or flagged as suspicious; see when SPF or DKIM alignment fails.
Note: Since Yahoo! and AOL have already restricted the use of their domains to send emails from other servers, other public email services will likely follow suit. That's why we recommend you to not use any public domain email address.Wrap up
If you use a public domain sender address, you may face the following issues:
- Your emails may bounce, as major mailbox service providers have implemented DMARC
- Your emails may resemble spam, as spammers use public domain sender addresses to send junk email
- Your recipients may not recognize your business
- Your emails may be left unopened and you won't be able to achieve the desired conversion
- Sometimes your emails may get marked as spam. This will affect deliverability for your future emails